Stuttgart 2012 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 20: Poster: Diagnostik

P 20.7: Poster

Donnerstag, 15. März 2012, 16:30–19:00, Poster.III

On the plasma chemistry of low-pressure Ar/N2/CH4 microwave discharges using an external cavity quantum cascade laser — •Dmitry Lopatik, Henrik Zimmermann, and Jürgen Röpcke — INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany

The volume chemistry of low-pressure molecular plasmas containing hydrocarbon precursors has been of great interest over the past decade. This type of plasmas offers a wide field of applications but however a number of processes and properties are far from being fully understood. In this case, the analysis of the fragmentation of the precursors and the monitoring of plasma reaction products can lead to a better understanding of plasma chemistry and kinetics. Absorption spectroscopy in the mid infrared spectral range provides a means to measure molecular species concentrations in the ground state. The recent availability of continuous wave external cavity quantum cascade lasers, (cw EC-QCL), which are widely tunable infrared radiation sources, has opened up a new approach for plasma chemistry studies and offers a great advantage for simultaneously detection of multiple absorption features within available spectral regions. In the present study we focus on the high resolution diagnostics of Ar/N2 microwave plasmas containing methane performed by an EC-QCL operating at 1300-1450 cm-1. Four stable molecules: CH4, C2H2, HCN and H2O were detected and its concentration behaviour systematicly investigated. The influence of process parameters, like gas mixture, pressure and power of the plasma on the chemical processes was in the center of interest.